Membrane phase behavior modulated by active actin-myosin composites

Our team is part of the interdisciplinary lab, Physics of Cells and Cancer , at the Curie Institute, a highly stimulating and dynamic research institute located in Paris city center.  

Our team has developed novel in vitro reconstitution systems (composed of purified proteins and model membranes) to study protein-driven membrane reshaping. To realize this project, our lab is equipped with cutting edge super-resolution microscopes. 

Dynamic networks of myosin motors and actin polymers attached to the plasma membrane of cells enable the cells to have precise, spatial-temporal control over their surface shape and the heterogeneity of the membrane composition. The actin cytoskeleton is physically coupled to the membrane by actin-membrane linkers, notably active linker, type I myosin motors (myo1). Myo1 plays a key role in various cellular processes involving dynamic reorganization of both actin and the membrane. Additionally, myo1 acts as a force dipole that cyclically generates mechanical forces at the actin-membrane interface. However, the precise mechanical effects of myo1's action on the dynamic reorganization of the actin-membrane coupled composite remain elusive. 

Our project aims to elucidate how the mechanical forces generated by myo1 motors modulate dynamic actin reorganization, and at the same time, impact the phase separation processes of the membrane, particularly at the critical point. To this end, we have generated nematic actin structures assembled on lipid membranes.  Recently, we have observed dynamic reorganization of actin filaments driven by myo1 motors .  

The goal of the internship is to study how the active actin-myosin flow impacts membrane phase separation processes. We will use fluorescence microscopy (TIRF) and super-resolution microscopy (STORM), as well as single lipid tracking to monitor the phase separation process. 

Our results will guide the theoretical description of myo1-driven actin reorganization in collaboration with Carles Blanch Mercader and Jean-Francois Joanny (Curie Institute). 

We are looking for highly motivated students  with backgrounds in biochemistry or  biophysics , who are interested in interdisciplinary research.